Multi-antenna wireless communication method and multi-antenna wireless communication device

Abstract

The wireless communication devices A and B determine the optimal diversity combining weight information that optimizes a diversity reception state at each antenna group A1, A2, . . . , AP through two-way training signal transfer between the wireless communication devices A and B. This optimal diversity combining weight information is set to each antenna of each antenna group A1, A2, . . . , AP. Wireless communication units A′, B′ perform spacial mapping of signals from antenna group A1, A2, . . . , AP using MIMO technology. Communication area can be enlarged by hierarchization MIMO using the optimal diversity combining weight information.

Description

TECHNICAL FIELD[0001]The present invention relates to a multi-antenna wireless communication method, a multi-antenna wireless communication system, and a multi-antenna wireless communication device, and more particularly, relates to a multi-antenna wireless communication method, a multi-antenna wireless communication system, and a multi-antenna wireless communication device, in which wireless communication is performed with MIMO (Multiple Input Multiple Output) or SIMO (Single Input Multiple Output) technology using a plurality of radios in transmitting side or in receiving side or both and in which an antenna group comprising multiple antennas is used at every transmitting / receiving circuit and each antenna group performs wireless communication with MIMO technology.BACKGROUND ART[0002]The thinness of the semiconductor process rule makes it possible that a plurality of radio circuits are implemented in one semiconductor chip. As a result, the adoption of MIMO technology has become m...

AI Technical Summary

Benefits of technology

[0065]In the present invention, along with the spatial multiplexing, diversity or beam forming of conventional MIMO technology, further beam forming technique using multi-antenna group is put together with these independently, and therefore a spot area where high throughput transmission of 100 Mbps or more using spatial multiplexing can be enlarged to a plane area. The communications area of VoIP system with conventional MIMO technology like diversity is much smaller than that of narrow-band wireless system such as conventional PHS system. On the other hand, the communication area equivalent to narrow-band wireless system such as conventional PHS system can be realized by the use of combination of conventional diversity and the beam forming according to the present invention.

[0066]In the present invention, the value optimum of diversity combining information in each wireless communication device is determined through two-way training signal transfer between wireless communication devices that perform transmission and reception, and therefore the value optimum of diversity combining information can be easily calculated, and a large MIMO gain can be obtained by performing data transfer by use of this value optimum of diversity combining information even when the number of antennas of the wireless communication device is large. The performance that is equivalent to that of present invention can be realized by conventional MIMO which uses channel matrix of large order, but from the point of cost, power consumption and the amount of arithmetic processing, the implementation of larger scale MIMO is not practical because enormous circuits including radios and baseband circuit is needed.

[0067]Further, the communications area in the conventional MIMO technique can be improved drastically without increasing transmit and receive circuit number if diversity combining in each antenna group is performed in a radio frequency band or without increasing cost and power consumption too much because conventional MIMO technique is just used, and individual antenna is substituted for each antenna group, and inherent beam transmission to the maximum eigenvalue can be implemented every antenna group.

[0068]Though in conventional broadband wireless system in which maximum throughput is greater than 100 Mbps, the area where high-throughput transmission of around 100 Mbps can be performed is almost like a spot, it becomes possible to cover whole service area with the area where high-throughput transfer around 100 Mbps can be performed according to the present invention.

[0069]Also, it is mandatory to share information about the channel matrix in the eigenbeam transmission of the conventional MIMO technology both in a transmitting side and in a receiving side, and applying this technology in fast fading environment is very difficult. However, according to the present invention, sharing the channel matrix between a transmitter and a receiver is unnecessary and it becomes possible to apply the eigenbeam transfer to the fast fading environment.

[0070]FIG. 46 shows a comparison of the reception level distributions at an initial acquisition stage between the conventional MIMO technology and the present invention. Here, it is assumed that wireless transmission line is Rayleigh fading environment, and the number of transmitting / receiving antennas of each wireless communication device is four. Additionally, the reception level distribution of SISO and MIMO with optimum weight is shown for the reference. Referring to FIG. 46, it is found that the improvement of the reception level in the initial acquisition state of the conventional MIMO technology compared with that of SISO is about 16 dB, which is deteriorated 11 dB compared with MIMO transmission gain with the optimum weight. This is because eigenbeam transfer cannot be performed in the initial acquisition state, and in this case, the improvement of the reception level can be obtained by use of transmission gain of 4-branch selection diversity.

Problems solved by technology

In most of the wireless system which MIMO technology has been introduced, the number of antennas of hand-held terminal is one in general because of power consumption and battery life.

In the case of this, high-speed transmission by use of multi-stream transfer cannot be achieved.

In the diversity gain of this extent, the great enhancement of the area where high-throughput transfer can be performed cannot be expected.

However, the amount of this improvement is small and the area in which throughput takes the value of almost 100 Mbps is limited to the surrounding area near AP and the range of the high-throughput transmission is around 10 m or less in this case after all.

However, the amount of this improvement is still small and the area in which throughput takes the value of almost 100 Mbps is limited to the surrounding area near AP and the range of the high-throughput transmission is around 10 m or less in this case after all.

The radius of service area of the wireless LAN system of IEEE802.11n is said to be around 100 m, however, the area where high-throughput transmission around 100 Mbps is achieved is limited to PAN (Personal Area Network) area in which the distance from AP is around 10 m or less.

However, the gain in transmitting / receiving signals is 12 dB extent at most, therefore great extension of the communication area will not be obtained.

In this case, the eigenvectors can be obtained by use of repetitive operation, and therefore the processing time for the calculation becomes critical.

In fast fading environment, a frequent transfer of the information of channel matrix is necessary, and this will cause deterioration of channel capacity of the system.

Therefore, in the conventional MIMO technology, the communications area is limited to the area where eigenbeam can be formed without initial acquisition.

In order to realize the true broadband wireless LAN system with which high-throughput transfer of around 100 Mbps can be performed at any point in the service area, the performance of conventional MIMO technology which uses the combination of beam forming and spatial multiplexing is not enough.

And there is no technology which provides enough performance of that.

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